V6R VRF 50Hz
41
P
art
3
- Con
tr
ol
7
Special Control
7.1
Oil Return Operation
In order to prevent compressors from running out of oil, the oil return operation is conducted to recover oil that has flowed
out of the compressor(s) and into the piping system. This operation is performed for all units including units that are in
standby.
When the outdoor unit is running in oil return, the digital display on outdoor main PCB will display “d0”.
Cooling Only/Main Cooling Oil Return Control
Timing of oil return operation:
Calculated oil discharge has reached to specified level. The higher the compressor frequency step is, the more oil
discharge.
Initial cumulative compressor operating time reaches 2 hours.
Cumulative compressor operating time reaches 8 hours.
Tables 3-7.1 and Tables 3-7.2 show component control during oil return operation in cooling only/main cooling mode.
Table 3-7.1: Outdoor unit and MS component control during oil return operation in cooling
only/main cooling mode
Component
Wiring diagram
label
Cooling oil return control
STEP1
STEP2
STEP3
ODU
Inverter
compressor
INV1
PI control, the minimum
step is as follows:
8-10HP 28Hz
12-22HP 61Hz
24-34HP 105HZ
36-60HP 165Hz
8-10HP 28Hz
12-22HP 61Hz
24-34HP 105HZ
36-60HP 165Hz
Minimum step(All outdoor unit
compressors are running).
Inverter fan 1
FANA
PI control(Cooling Only)
Inverter fan 2
FANB
Four way valve
ST1
ON
Back to the state before oil return
Electronic
expansion valve
EEVA
Compressor operation, 2880pls
Compressor not operation, initial 135pls, then adjusted according to the module temperature
EEVC
0pls
Compressor operation, 17pls→ +8pls per 20S based on high
pressure or discharge temperature.
Compressor not operation, 0pls.
Solenoid valve
SV5
ON
Refer to normal operation control
SV8A
ON
SV7
OFF
Turn ON/OFF based on the low
pressure and the high pressure etc.
MS01
Electric
ball
valve
EVBA
2950pls
EVBB
0pls
EVBC
2950pls
Electronic
expansion valve
EEVA
0pls
MS04-12
Solenoid valve
SV(n)A
ON
SV(n)B
OFF
SVP
OFF
Electronic
expansion valve
EEVA
0pls
Ending conditions
End if startup time arrives
150S.
End if startup time arrives 6
min or the compressor
discharge volume
≥
Target
value for 4min.
After 30S.
